<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="text" name="first">
    <select name="symbol" id="symble">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">*</option>
        <option value="/">/</option>
    </select>
    <input type="text" name="second">
    <input type="submit" >
    <label id="rusult"></label>
</body>
<script>
    function returnResult(){
        var firstNun = document.getElementById('first').value;
        var sympol = document.getElementsByName('symbol').value;
        var secondNun = document.getElementById('second').value;
        var result = 0;
        switch(sympol){
            case '+':
                result = firstNun+secondNun;
                break;
            case '-':
                 result = firstNun-secondNun;
                break;
            case '*':
                result = firstNun*secondNun;
                break;
            case '/':
                result = firstNun/secondNun;
                break;

        }
        document.getElementsById('result').innerHTML = result;
    }
</script>
</html>